Conventional valves employed in conjunction with equipment for delivering a flow of abrasive materials, such as sand blasting equipment, normally have a relatively short working life. Such valves generally comprise a valve body which includes an opening therein, and a plate member housed in said body and which includes an opening therein. The plate member can be manipulated from outside of the valve body to open the valve in which case the opening in said plate member is moved into alignment over the opening in the valve body so as to allow abrasive material to flow through the valve. The valve is closed to stop flow of abrasives therethrough by merely manipulating the plate member so that the opening therein is moved out of alignment and away from the opening in the valve body so that said openings in no way overlap. As the valve is moved from its open position to its closed position and vice versa, the plate member, specifically that area surrounding the opening therein, comes into direct contact with abrasive or caustic material. This action causes wear about the opening in the plate member. The amount of wear produced will depend upon the type of abrasive or caustic employed, the rate of flow thereof through the valve and the number of times the valve is opened and closed. Eventually, and usually within a relatively short time, the abrasive etc. will cause sufficient wear of the plate member so that the opening therein will be so large as to make it impossible to close off the valve. At this stage, the valve becomes useless and can only be made operable by replacing the worn out plate member with another plate member. Depending upon the design of the valve, this is at the least, an expensive and frequent maintenance operation since the plate members required wear out quickly and are costly. At the most, it is impossible to replace the worn out plate members andn thus, the worn valve would have to be discarded and replaced with a new valve.